<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div>
        <input type="text" v-model="num1">
        <input type="text" v-model="num2">
        <input type="button" value="加" @click="f(1)">
        <input type="button" value="减" @click="f(2)">
        <input type="button" value="乘" @click="f(3)">
        <input type="button" value="除" @click="f(4)">
        <h3>结果：<span>{{result}}</span></h3>
    </div>
</body>
<script src="https://cdn.staticfile.org/vue/2.2.2/vue.min.js"></script>
<script>
    let v = new Vue({
        el:"body>div",
        data:{
            info:"",
            result:"",
            num1:"",
            num2:""
        },
        methods:{
            f(x){
                if (isNaN(v.num1) || isNaN(v.num2)){
                    v.result = "输入有误"
                    return;
                }
                switch (x) {
                    case 1:
                        v.result = v.num1*1 + v.num2*1;
                        break;
                    case 2:
                        v.result = v.num1 - v.num2;
                        break;
                    case 3:
                        v.result = v.num1 * v.num2;
                        break;
                    case 4:
                        v.result = v.num1 / v.num2;
                        break;
                }
            }
        }
    })
</script>
</html>
